The e-mail from an old friend who runs a white-water rafting company was too enticing to resist: We’re running a new river in India’s remote east, he wrote. Join us.

It sounded like a rush. It turned out to be much more. In six days, we covered 72 miles of the Kameng River and shot some 100 rapids.

We plunged through roiling caldrons of white water that lifted the adrenaline level to truly yee-ha moments. And I took more than one unwilling swim in the chilly water.

The Kameng sweeps through the Valley of the Hornbills in pristine rain forest. Elsewhere it passes below tiny bamboo villages of the Nishi tribe, whose men hunt the magnificent birds for the colorful bills that adorn their headgear and who carry machetes in monkey-fur scabbards.

We saw nature as it was meant to be — raw and lush. But we also witnessed its fragility: a simple farmer burns away an entire mountainside to work a small patch of land; bulldozers send rockslides tumbling down mountain slopes as they carve out a road; an energy-hungry nation begins work to dam yet another free-flowing river.

White-water rafting is a popular adventure sport in India. About 20 rivers spilling from the Himalayas toward the Indian plain are commercially rafted, with trips ranging from a few hours to two weeks. Some 30,000 people a year make the short but thrilling run on the Ganges above the Hindu holy town of Rishikesh, just a few hours drive from New Delhi.

The Kameng River is in the state of Arunachal Pradesh on India’s northeastern frontier, more than 1,000 miles from the capital. The state was a battleground in the 1962 Indo-China war, and its ownership still is disputed. India kept it off-limits to foreigners until recently and has done little for its development. Even Indians need a permit to enter.

Quite the team

Our expedition was only the third time rafts and kayaks have been down the Kameng. Six professionals explored it in late 2007. A larger group of international adventurers ran it in March 2008.

Anvesh Singh Thapa of the startup company Expeditions India, who was on both those trips, teamed up with Yousuf Zaheer of Himalayan River Runners for the first commercial run. Yousuf offered it to old friends and clients.

Our team of 10 was different from the earlier groups. Ranging in age from 30 to 65, some of us found our wetsuits bulged and sagged in the wrong places.

Among us were two female investment brokers from London (one had never seen a sleeping bag from up close), an Indian air force fighter pilot with a passion for wildlife photography, and Romulus Whitaker. Born in New York, Rom is India’s foremost herpetologist, conservationist and the founder of a crocodile farm in southern India with 7,000 reptilian residents. He came to look for pit vipers, which thankfully he didn’t find.

“This river has everything,” Anvesh told us — natural beauty, tribal culture, and abundant rapids, many of them Class IV-plus (Class V being the highest). He rated it among his top three favorites in India and said his international colleagues ranked it among Asia’s top 10.

Ready, set, go

It took us four days to get to the put-in point. We flew from New Delhi to Guwahati, the state capital of Assam, then drove through eastern Assam’s flat tea-growing country. Our jeeps turned north toward Bhalukpong, the single-street border town whose biggest business is the Casino liquor store. The last 40 miles from the town of Seppa was a grueling six-hour drive along a rutted road muddied by streams trickling down the steep mountains.

As we set our rubber crafts in the water at Marjingla, the entire village was on hand. One boy asked if the boats were made from dead elephants. An elder tried to barter village girls for the two London women, waving his machete in a courtship dance — to the titters and guffaws of onlookers.

When Arvind Bhardwaj, one of the river guides, told him the women were married with children, he shot back, “Don’t worry — I’ll give them plenty more.”

Once on the water, the rapids came one after the other.

We paddled downstream three to four hours a day. We hurtled between huge boulders and splashed through towering waves that drenched us. We pitched like cork in the torrent and sometimes got tossed off our perches on the rafts’ pillions, holding on only by our toes jammed under the rubber.

Anvesh took the lead in his orange kayak “Fat Face,” scouting each rapid for eddies, holes and other lurking dangers.

Dangers abound

On the first day, our 16-foot raft was impaled on a rock and quickly filled with gushing water. As it tipped on its side, the current dragged three of us overboard.

We had been well instructed: If you fall in, point your toes downstream, lean back — and smile. We swam to the riverbank with little difficulty.

We pitched camp in the early afternoons, erecting our two-person tents on sandy riverside patches. Shouki, the cook, produced small miracles from the kitchen tent. We ate around a driftwood campfire, draped our thermal underwear near the flames to dry and swapped stories until climbing into our sleeping bags. Each morning after decamping and packing the boats we scoured the beach for garbage, ensuring no evidence of our presence was left behind.

At one camp at the mouth of a small stream, we found deep footprints in the sand and mud of elephants that had forged the river a few hours before. We also found fresh leopard tracks. On Rom’s advice, we set up camp off the elephant’s path and lit bonfires on either side of our campsite to discourage visitors.

If you see a big guy coming, Rom told us, race for the rocks where elephants cannot run.

Nothing would save you from leopards, he said, but they have tastier prey than us.

All in a name

On the fourth day we entered a gorge that runs through the Eagles Nest Wildlife Sanctuary. A green wall of vegetation soared 1,000 feet above the water. Orchids wrapped themselves around hardwoods set amid wild banana trees, bamboo and ferns. On the river, boulders were worn smooth and sculpted into modern artworks.

We began keeping count of the rapids — only the big ones — toting up 41 in two days, while Anvesh’s altimeter showed the river dropping 150 feet. Some rapids looked like out-of-control escalators.

Rapids normally acquire names after an unusual feature or event, and earlier expeditions had assigned appellations to a few of the Kameng’s tougher passages, such as the Sock Sucker and the Gruesome Geyser (not for old geezers — the amateurs took the safer route overland).

Our group left its tag on a few, including the river’s last major rapid: The Ejector, so named after a massive wave catapulted me from the raft as if I had hit the eject button on a jet fighter.

It was like being trapped in a washing machine. My life vest lifted me to the surface, but the swirling river dragged me down again before I could catch a full breath, and kept me under longer than I cared to stay. When I emerged gasping a second time, I straightened on my back and floated toes-first until Arvind threw me a rope and hauled me into his raft.

I was still smiling, and ready for more. But an hour later we hoisted the boats onto a beach for the last time, deflated them and climbed into the waiting jeeps to take us to our first hot showers.

If You Go

RAFTING COMPANIES: There are many, but not all use experienced guides who will keep your boat upright. Among the biggest, with a wide variety of rafting and trekking options, are Himalayan River Runners (www.hrrindia.com), Aquaterra Adventures (www.treknraft.com) and Red Chilli Adventure (www.redchilliadventure.com). Expeditions India (www.expeditionsindia.com) intends to focus on more challenging trips.

EQUIPMENT: Companies provide tents, life jackets and helmets, wetsuits when needed for cold rivers, and surprisingly good food. Rafters may be asked to bring sleeping bags, flashlights and lots of mosquito spray.

EXPERIENCE NEEDED: Very little. The river guides do all the real work, while the paddlers’ job is to provide the muscle. Knowing how to swim is not required, and you don’t need to be in top physical shape.

COSTS: The most popular short trip on the upper Ganges is about $70 for two days and one night in a beach camp including meals. A spectacular 12-day trip on the Zanskar River in the Himalayas is about $1,550 per person.

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